Packing sleeve for rock drills



April 30, 1957 a. E. R. LGFQVIST ETAL 2,790,624

' PACKING SLEEVE FOR ROCK DRILLS Filed Oct. 21, 1953 2 Sheets-Sheet 1 INVENTORS V, v by M +Q -V April 30, 1957 a. E. R. LbFovlsT ETAL 2,790,624

menus SLEEVE FOR ROCK DRILLS Filed 060. 21, 1953 2 Sheets-Sheet 2 Fig 4 I NVEN TORS United States Patent PACKINGSLEEVEFORROCK DRILLS Bengt Erik Ragnwald Liifqvist and mam 'Berggren, Sandviken, Sweden, assignors to Sandvikens Jernverks Aktiebolag, Sandviken, Sweden, a corporation of Sweden Application October 21, 19 53, SerlaFNo. 387573 Claims priority, application Sweden-Octob'erZS, 1952 s Claims. icl. 255- 64 In *rock drills and especiallyin percussion drills in whichflushingmediumis pas'sed through a flushing tube into a flushing channel of thedrill it often happens that flushing medium, usually water, "leaks into the drilling machine, notwithstanding that the flushing tube discharges at a substantial distance into the flushing channel in the shank of the drill. As a resuln a'mist-of steam and/or finely sprayed water is formedwhieh causes corrosion in the turning mechanism and other parts of the drilling machine. Besides, a part of the-flushing medium is wasted and does-not serve'to fiush away the drilling meal. -Due to thefrequent occurrence of toos'mall a play between 'the' flushing tubean'd the wall of the flushing channel, and

especially due to the frequent formation of aburr at'the end of the drill, breakage of the'flu'shing tube frequently occurs, partly on account of the turning of the drill in relation to the flushing tubeand'partly on account'of the "longitudinal movements of the "drill in relation to the flu'shingtube.

It has been attempted to solve'this'problem by providing the end part of the flushing channel in the shank of the drill. with'a packing or a'bushing around the flushing tube, which packing is fastened to the wall'of the flushing channel by gluing, vulcanization, or the like. It is true that this, for a limited time,-accornplishes the necessary sealing against leakage of flushing'water and givesa certain degree of protection against breakage of the flushing .ichhization 'also'involves heating' the drill which-maybe accompanied by'an'uhdesirable changein texture of the packing andthe drill.

It has been proposed toi-nserta -paeking of elastic mate- 'rial into the end part of the channel-around the flushing tube byother fastening methods,-as for instance bysqueezing, but the elasticity of the material which squeezes the packing against the Walls of the flushing channel is too small to give a secure fastening to the wall, otherwise such large dimensions must be given to this packing in order to get a satisfactory spring tension that this expedient cannot be applied to flushing tubes and channels of the usual sizes.

The present invention relates to a new type of packing sleeve which eliminate the above-mentioned drawbacks. It relates to a packing sleeve for rock drills with a flushing channel, designed to prevent substantial leakage of flushing medium between the shank of a drill and the drilling machine and is characterized in that the sleeve is spring reinforced and is arranged to be pressed against the wall of the flushing channel near its end in the shank of the drill, the pressing force being obtained by means of spring force in the reinforcement.

"Ice

Such a device provides an easily removableipacking, which on account of its elastic contact against the wall of the flushing channel and in spite of the above-mentioned longitudinal movement betweenflushing tube and channel does not fail even after'a long period'of use. The spring reinforcement provides a sufiicient spring force against the Wall of the channel that substantial displacement from its fastening position does not occur. It does not require a time'consuming or material-deteriorating operation for its installation and it provides an efiective seal against discharge of flushing medium from the shank a drill into the drilling machine.

The sleeve is suitably made of some relatively sof -t, flexible, elastic material, as for instance naturalorsyntheric rubber or other durable, flexible material such as leather or the like and it is reinforced with a relatively hard resilient insert such as a spring form'edof metal, h'ard rubber or the like. An especially advantageous reinforcemeat is metallic spring which-may be'in the form of one or more spiral springs, flat springs or a slotted metallic tube for that part of the flushing channel Where the sleeve is to be fastened. The sleeve is suitably given a form corresponding with the form of that part of the channel Where the sleeve is to be situated. It may be of different lengths and in certain cases it may extend only a short distance into the end part of the channel in the shank of the drill and it may be completely cylindrical or completely conical, or partly cylindrical andpar'tly conical. The reinforcement may be secured'to the rest of the'sleeve by vulcanization or in any other suitable way. For example, the sleeve may be formed of rubber with'the spring embedded in it. The spring 'reinforcement may extend over the whole sleeve or even beyond the end of the sleeve in order to obtain a larger spring force against-the walls of the channel.

The embodimentin which the reinforcement consists ofa spiral spring has the special advantage of being capable of being introduced into its place in the channel by a twisting movement, and this makes it possible to exe'rt 'a strong spring force in its seated'position without any special compressing or other manipulation.

Thereinforccznent may also consistof resilient tubes or rings which may, if desired, bevulcanized'into the sleeve. As above mentioned, the reinforcem'e'nt'may also consist of slotted tubes of different kindsyfor' example clamping "rings, and the latter may be slotted-substantially alonga 'generatrix in the cylindrical body. Themat'eri-al ofthe reinforcement may consist of metal' or other suitable-resilient material which generally is harder and more strongly resilient than the bodyofthe sleeve.

The packin sleevev may be provided withiecesses"in its outer surface which-are completely surroundeclby those parts of the sleeve which contain the reinforcement. In "fastened position .these "recesses fortnfcl'osed pockets 'fwi'thlthewall of theflushi'ng channel which-exert afsuct-ion force-tending to"pi-event ii'isplaeement of the sleeve. The effectiveness of these closed pockets is considerably improved by the presence of the flushing water.

The sealing action of the sleeve may be improved by providing it with one or more beads or ridges which bear against the flushing tube. These ridges may be of the same or a similar material as the rest of the sleeve and may extend to the periphery of the flushing tube.

Several illustrative embodiments of the packing sleeve according to the invention are shown in the accompanying drawings in which:

Fig. l is a longitudinal section through a packing sleeve, positioned around a flushing tube in the shank of the drill;

Fig. 2 shows the same sleeve, partly in section;

Fig. 3 is an end view of the sleeve, seen in drilling direction;

Fig. 4 shows another sleeve in section in operative position;

Fig. 5 is a side elevation of the sleeve of Fig. 4;

Fig. 6 shows a sleeve, partly in section, reinforced by means of a slotted tube;

Fig. 7 shows a sleeve, reinforced by means of a spiral spring, and

Fig. 8 is an enlarged section similar to Fig. 4 more clearly showing the reinforcing element in the sleeve.

In the embodiments illustrated in Figs. 6 and 7, the reinforcement extends beyond the packing material of the sleeve.

Referring to Fig. 1, the flushing tube 12 extends into the flushing channel 15 in the shank of a drill 11 and into the alined channel 10in the percussion piston 13. During the'opcration of percussion drilling, the drill 11 will turn about its longitudinal axis in relation to the tube 12 and longitudinal vibrations due to the percussions will cause a certain relative movement between the flushing tube and the drill. The packing sleeve 14 presses against the wall of the flushing channel 15 near its end in the shank of the drill, which end usually is cylindrical, conical or doubleconical. The sleeve 14, which may consist of natural or synthetic rubber, is reinforced by the spiral steel spring 16, extending the full length of the sleeve. This spring retains the sleeve against the Wall of the flushing channel 15. A satisfactory fit must exist between sleeve and flushing tube 12 in order to prevent flushing water from leaking into the drilling machine. Fig. 1 shows a narrow space between the outer surface of the tube 12 and the inner surface of the packing sleeve 14. The showing is exaggerated. In practice this space is of only capillary thickness and is closed by the water so that practically no water escapes in the direction of the piston 13.

As shown in Figs. 2 and 3, the sleeve 14 is shaped to fit the corresponding part of the flushing channel.

Figs. 4, 5 and 8 show another type of packing sleeve 17 with the reinforcement 18 consisting of harder material than the rest of the sleeve. The recess 20 between the ridges 19, 19 forms a closed space between the sleeve and the wall of the channel 15 which tends to prevent displacement of the sleeve. A variety of other types of surface recesses might be used. As shown in Fig. 8 the reinforcement is a hard rubber spring 18 embedded in the softer rubber body of the sleeve. In all types of sleeves it is important that the diameter of those parts of the sleeve where the reinforcement is arranged is greater than the corresponding diameter of the flushing channel so that the sleeve when introduced into the channel will engage the wall thereof with resilient pressure.

Fig. 6 shows a sleeve 22 reinforced by a slotted metal tube 21 which extends beyond the end of the sleeve. This sleeve is provided with a head or ridge 23 to improve the sealing between it and the flushing tube 12.

Fig. 7 illustrates a sleeve 24 similar to that illustrated in Fig. 6 excepting that it is reinforced by means of a spiral spring 25 extending beyond the end thereof similar to the reinforcing ring 21 of Fig. 6 and has a ridge 26 adjacent the middle of its length.

We claim:

1. A sleeve adapted to be placed between the flushing tube of a drilling machine and the flushing channel of a drill, said sleeve, tube and channel all being circular in cross-section, said flushing tube extending from the drilling machine into the flushing channel of the drill in the coupled position of the machine and drill, the outer diameter of the extending portion of the flushing tube being less than the inner diameter of the surrounding part of the flushing channel thus leaving a space therebetween, said sleeve being formed of elastic material and having a spiral resilient reinforcing element embedded therein, said sleeve being positioned around the flushing tube in said channel, said element being tensioned to press the elastic material outwardly against the wall of said channel, the outer surface of the sleeve having a form substantially corresponding with the surrounding surfaceof the channel, the inner diameter of said sleeve having in inserted position a diameter substantially corresponding to the outer diameter of the flushing tube.

2. A sleeve as defined in claim l in which the flexible material is a relatively soft elastic material and in which the reinforcing element is a relatively hard elastic material.

3. A sleeve as defined in claim 1 in which said flexible material is rubber and said reinforcing element is metal.

4. A sleeve as defined in claim 1 in which the reinforcing element is coextensive with the flexible material.

5. A sleeve as defined in claim 1 in which the reinforcing element extends the entire length of the flexible material and a substantial distance beyond one end thereof to obtain a larger spring force against the wall of the channel.

6. A sleeve as defined in claim 1 in which at least one end portion thereof has frusto-conical inner and outer surfaces and the corresponding portions of the tube and channel are frusto-conical.

7. A sleeve as defined in claim 1 in which one end portion thereof has cylindrical inner and outer surfaces and the other end portion has frusto-conical inner and outer surfaces and the corresponding parts of the tube and channel are cylindrical and frusto-conical respectively.

8. A sleeve as defined in claim 1 in which the outer surface of the sleeve is provided with two longitudinally spaced apart annular ridges shaped to fit the surface of the channel.

References Cited in the file of this patent UNITED STATES PATENTS 1,657,317 Potter Jan. 24, 1928 2,162,104 Mosher June 13, 1939 2,164,886 Renfer July 4, 1939 2,643,641 Huffman June 30, 1953 FOREIGN PATENTS 275,550 Germany June 20, 1914 703,031 Germany Feb. 26, 1941 

